Split contact sensor for a heat-assisted magnetic recording slider

ABSTRACT

An apparatus comprises a slider having an air bearing surface (ABS), a leading edge, and a trailing edge opposing the leading edge. A writer having a write pole is situated at or near the ABS. A near-field transducer (NFT) is situated at or near the ABS and between the write pole and the leading edge of the slider. An optical waveguide is configured to couple light from a laser source to the NFT. A contact sensor is situated between the write pole and the trailing edge. The contact sensor comprises a first ABS section situated at or near the ABS, a second ABS section situated at or near the ABS and spaced apart from the first ABS in a cross-track direction by a gap, and a distal section extending away from the ABS and connecting the first ABS section with the second ABS section.

RELATED PATENT DOCUMENTS

This application is a continuation of U.S. patent application Ser. No.16/524,512, filed Jul. 29, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/134,021, filed Sep. 18, 2018, now U.S. Pat. No.10,410,660, which are incorporated herein by reference in theirentireties.

SUMMARY

Embodiments are directed to an apparatus comprising a slider having anair bearing surface (ABS), a leading edge, and a trailing edge opposingthe leading edge. A writer having a write pole is situated at or nearthe ABS. A near-field transducer (NFT) is situated at or near the ABSand between the write pole and the leading edge of the slider. Anoptical waveguide is configured to couple light from a laser source tothe NFT. A contact sensor is situated between the write pole and thetrailing edge. The contact sensor comprises a first ABS section situatedat or near the ABS, a second ABS section situated at or near the ABS andspaced apart from the first ABS in a cross-track direction by a gap, anda distal section extending away from the ABS and connecting the firstABS section with the second ABS section.

Embodiments are directed to an apparatus comprising a slider having anABS, a leading edge, and a trailing edge opposing the leading edge. Awriter having a write pole is situated at or near the ABS. An NFT issituated at or near the ABS and between the write pole and the leadingedge of the slider. An optical waveguide is configured to couple lightfrom a laser source to the NFT. A contaminant buildup region fans outfrom the NFT in a cross-track direction along the ABS, past the writepole, and towards the trailing edge of the slider. A contact sensor issituated between the write pole and the trailing edge. The contactsensor comprises a first ABS section situated at or near the ABS, asecond ABS section situated at or near the ABS and spaced apart from thefirst ABS in a cross-track direction by a gap, and a distal sectionextending away from the ABS and connecting the first ABS section withthe second ABS section. The gap is sufficient in size such that thefirst and second ABS sections are outside of the contaminant buildupregion.

The above summary is not intended to describe each disclosed embodimentor every implementation of the present disclosure. The figures and thedetailed description below more particularly exemplify illustrativeembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a HAMR slider with which variousembodiments disclosed herein may be implemented;

FIG. 2 is a cross-sectional view of a HAMR slider with which variousembodiments disclosed herein may be implemented;

FIGS. 3A-3C are simplified side views of a writer portion of the HAMRslider illustrated in FIGS. 1 and 2;

FIG. 4 is an exaggerated illustration of a laser-induced protrusiondeveloped at the ABS of a HAMR slider in accordance with variousembodiments;

FIG. 5 is an AFM (Atomic Force Microscope) image of a HAMR slidershowing a contaminant buildup region of the slider;

FIG. 6A is a schematic of various components of a HAMR slider, includinga split contact sensor, situated at or proximate an ABS of the slider inaccordance with various embodiments;

FIG. 6B is a cross-sectional view of the split contact sensor shown inFIG. 6A;

FIG. 6C shows a dielectric material disposed between a section of thesplit contact sensor of FIGS. 6A and 6B and a structure of the slider inaccordance with various embodiments;

FIG. 7 shows contact sensor signals generated by a conventional contactsensor with and without contaminant buildup;

FIG. 8 shows contact sensor signals generated by a split contact sensoraccording to various embodiments with and without contaminant buildup;

FIG. 9 is a perspective view of a split contact sensor in accordancewith various embodiments;

FIG. 10 is a cross-sectional view of a split contact sensor inaccordance with various embodiments; and

FIG. 11 is a perspective view of a split contact sensor in accordancewith various embodiments.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

The present disclosure generally relates to heat-assisted magneticrecording (HAMR), also referred to as energy-assisted magnetic recording(EAMR), thermally-assisted magnetic recording (TAMR), andthermally-assisted recording (TAR). This technology uses a laser sourceand a near-field transducer (NFT) to heat a small spot on a magneticdisk to near or above the Curie temperature during recording. The heatlowers magnetic coercivity at the spot, allowing a write transducer tochange the orientation of a magnetic domain at the spot. Due to therelatively high coercivity of the medium after cooling, the data is lesssusceptible to paramagnetic effects that can lead to data errors.

Embodiments of a HAMR head 100 that can incorporate a split contactsensor of the present disclosure are illustrated in FIGS. 1 and 2. Asshown, the head 100 (also referred to as a slider) includes a lightsource (e.g., a laser diode) 102 located proximate a trailing edgesurface 104 of the slider body 101. An optical wave (e.g., a laser beam)120 generated by the light source 102 is delivered to an NFT 112 via anoptical waveguide 110. The NFT 112 is aligned with a plane of an airbearing surface (ABS) 114 of the head 100, and one edge of a read/writehead 113 is on the ABS 114. The read/write head 113 includes at leastone writer and at least one reader. In some embodiments, multiplewriters (e.g., 2 writers) and multiple readers (e.g., 3 readers) can beincorporated into the read/write head 113. The ABS 114 faces, and isheld proximate to, a surface 117 of a magnetic medium 118 during deviceoperation. The ABS 114 is also referred to as a media-facing surface.

The light source 102 in this representative example may be an integral,edge firing device, although it will be appreciated that any source ofelectromagnetic energy may be used. For example, a surface emittinglaser (SEL), instead of an edge firing laser, may be used as the source102. A light source may also be mounted alternatively to other surfacesof the head 100, such as the trailing edge surface 104. While therepresentative embodiments of FIGS. 1 and 2 show the waveguide 110integrated with the head 100, any type of light delivery configurationmay be used. As shown in FIG. 1, the laser diode 102 is shown coupled tothe slider body 101 via a submount 108. The submount 108 can be used toorient and affix an edge-emitting laser diode 102 so that its output isdirected downwards (negative y-direction in the figure). An inputsurface of the slider body 101 may include a grating, and opticalcoupler or other coupling features to receive light from the laser diode102.

When writing with a HAMR device, electromagnetic energy is concentratedonto a small hotspot 119 over the track of the magnetic medium 118 wherewriting takes place, as is shown in the embodiment of FIG. 2. The lightfrom the light source 102 propagates to the NFT 112, e.g., eitherdirectly from the light source 102 or through a mode converter or by wayof a focusing element. FIG. 2, for example, shows an optical coupler 107adjacent the light source 102, which is configured to couple lightproduced from the light source 102 to the waveguide 110.

As a result of what is known as the diffraction limit, opticalcomponents cannot be used to focus light to a dimension that is lessthan about half the wavelength of the light. The lasers used in someHAMR designs produce light with wavelengths on the order of 700-1550 nm,yet the desired hot spot 119 is on the order of 50 nm or less. Thus, thedesired hot spot size is well below half the wavelength of the light.Optical focusers cannot be used to obtain the desired hot spot size,being diffraction limited at this scale. As a result, the NFT 112 isemployed to create a hotspot on the media.

The NFT 112 is a near-field optics device configured to generate localsurface plasmon resonance at a designated (e.g., design) wavelength. TheNFT 112 is generally formed from a thin film of plasmonic material on asubstrate. In a HAMR head 100, the NFT 112 is positioned proximate awrite pole 226 of the read/write head 113. A yoke 228 is positionedadjacent to, and magnetically couples with, the writer pole 226. The NFT112 is aligned with the plane of the ABS 114 parallel to the surface 117of the magnetic medium 118. The waveguide 110 and optional modeconverter and/or other optical element directs electromagnetic energy120 (e.g., laser light) onto the NFT 112. The NFT 112 achieves surfaceplasmon resonance in response to the incident electromagnetic energy120. The plasmons generated by this resonance are emitted from the NFT112 towards the magnetic medium 118 where they are absorbed to create ahotspot 119. At resonance, a high electric field surrounds the NFT 112due to the collective oscillations of electrons at the metal surface(e.g., substrate) of the magnetic medium 118. At least a portion of theelectric field surrounding the NFT 112 gets absorbed by the magneticmedium 118, thereby raising the temperature of a spot 119 on the medium118 as data is being recorded.

The waveguide 110 shown in FIG. 2 includes a layer of core material 210surrounded by first and second cladding layers 220 and 230. The firstcladding layer 220, also referred to as a top cladding layer, is shownproximate the NFT 112 and the write pole 226. The second cladding layer230, also referred to as a bottom cladding layer, is spaced away fromthe first cladding layer 220 and separated therefrom by the waveguidecore 210. The core layer 210 and cladding layers 220 and 230 may befabricated from dielectric materials, such as optical grade amorphousmaterial with low thermal conductivities. The first and second claddinglayers 220 and 230 may each be made of the same or a different material.The materials are selected so that the refractive index of the corelayer 210 is higher than refractive indices of the cladding layers 220and 230. This arrangement of materials facilitates efficient propagationof light through the waveguide core 210. Optical focusing elements (notshown) such as mirrors, lenses, etc., may be utilized to concentratelight onto the NFT 112. These and other components may be built on acommon substrate using wafer manufacturing techniques known in the art.The waveguide 110 may be configured as a planar waveguide or channelwaveguide.

As was previously discussed, laser light produced by the laser 220 iscoupled to the NFT 112 via the waveguide 222. The NFT 112, in responseto the incident laser light, generates a high power density in anear-field region that is directed to the magnetic storage medium 118.This high power density in a near-field region of the NFT 112 causes anincrease in local temperature of the medium 118, thereby reducing thecoercivity of the magnetic material for writing or erasing informationto/at the local region of the medium 118. A portion of the laser lightenergy communicated to the NFT 112 is absorbed and converted to heatwithin the slider 100. This heating results in thermal expansion of theABS materials, protrusion at the ABS 114, and a change in bothhead-media clearance and head-media separation. In addition to the NFT112, the slider 100 typically includes additional heat sources that cancause further thermal expansion and protrusion of the ABS 114. Suchadditional heat sources, when active, include one or more of the writepole 226 (and writer coil), writer heater, and reader heater.

FIGS. 3A-3C are simplified side views of an NFT/write pole region of theslider 100 illustrated in FIGS. 1 and 2. The portion of the slider 100shown in FIGS. 3A-3C includes the write pole 226, NFT 112, and a portionof the ABS 114. FIGS. 3A-3C show general protrusion progression of aportion of the slider ABS 114 in response to activation of differentheat sources within the slider 100. These different heat sources includethe write coil of the writer, the writer heater, and the laser whichproduces the optical energy converted to heat by the NFT 112.

In FIG. 3A, the slider 100 is shown in a non-thermally actuated state.In this state, the laser, writer heater, and writer coil of the writerare all off. Thus, the slider 100 attains a default, non-actuatedshape/state establishing a default distance between the ABS 114 of theslider 100 and the surface of the magnetic storage medium 118. Thisdefault distance is illustrated by an air gap 270.

FIG. 3B illustrates the slider 100 in a partial-thermally actuatedstate, which is not a typical operational state but is shown forillustrative purposes. In this state, the writer heater and the writercoil of the writer are on, but the laser is off. In response toactivation of the writer heat sources (write pole 226, return pole) andwriter heater, the ABS 114 at and surrounding the NFT/write pole regionof the slider 100 protrudes into the air gap 270. Thus, the air gap 270and the distance between ABS 114 and the medium surface 118 decreases.The dashed line in FIG. 3B indicates the default state/shape of ABS 114depicted in FIG. 3A.

The magnitude of ABS protrusion of the slider 100 is furthered increasedby the additional activation of the laser, as shown in FIG. 3C. Theadditional heat produced by the NFT 112 in response to the incidentlaser light further expands the ABS 114, causing the ABS 114 to protrudefurther into air gap 270. It can be seen in FIGS. 3A-3C that the stroke,or magnitude, of the ABS protrusion of the slider 100 changes in sizeand shape with introduction and removal of heat to/from the ABS 114.

FIG. 4 is an exaggerated illustration of a laser-induced protrusiondeveloped at the ABS 114 of a HAMR slider 100 in accordance with variousembodiments. More particularly, the protrusion of the slider ABS 114shown in FIG. 4 is referred to herein as Laser-induced Writer Protrusion(LIWP). As a shown in FIG. 4, the region of LIWP encompasses a writepole 226 (e.g., write pole) and an NFT 112 of the slider. LIWPrepresents the full excursion of the protrusion developed at the ABS 114due to heating of the NFT 112 by excitation of the laser and other heatsources (e.g., the write pole 226 and writer heater). The reader 204 canalso be subject to displacement by the ABS protrusion resulting fromexcitation of the laser of the slider. Protrusion of the slider ABS 114due to laser/NFT heating in the region that encompasses the reader 204is referred to herein as Laser-induced Reader Protrusion (LIRP). Becausethe reader 204 is situated away from the NFT 112/write pole 226,allowing for dissipation of laser-induced heat, LIRP is not aspronounced as LIWP. However, LIRP is quite noticeable and impacts readerperformance. It is noted that the features shown in FIG. 4 are not drawnto scale.

LIWP is understood to include two protrusion components. The firstcomponent of LIWP is a broad protrusion component, referred to herein asBroad Laser-induced Writer Protrusion (BLIWP). As the term implies, arelatively broad region of the ABS 114 surrounding the write pole 226and NFT 112 expands to form a protruded region (volume) R1 (114 a) inresponse to the heat generated by the NFT 112 and the write pole 226(and writer heater). The second component of LIWP is a local protrusioncomponent, referred to herein as Local Laser-induced Writer Protrusion(LLIWP). LLIWP is a small and narrow protrusion (relative to the BLIWP)that extends from the BLIWP in a direction towards the surface of themagnetic recording medium 118. As can be seen in FIG. 4, the BLIWPcomponent encompasses a significantly larger volume (in region R1 114 a)of ABS material relative to that (in region R2 114 b) of the LLIWPcomponent. Evaluation of experimental sliders has revealed that LIWPtypically ranges between about 2 and 4 nm, while LLIWP typically rangesbetween about 1 to 2 nm (<2 nm). It is understood that, although each ofLIWP, BLIWP, LLIWP, and LIRP involves expansion of a volume of ABSmaterial, these protrusion parameters are measured in terms of adistance (in nanometers) extending from the ABS 114 and along a planenormal to the ABS 114 in a direction towards the recording medium 118.

An important function of a hard disk drive (HDD) is to accurately setthe clearance between the slider and the surface of the magnetic storagemedium of the HDD in order to maintain the written bit size, and thusmaintain areal bit density. Toward this end, various techniques havebeen developed to set clearance that involve incrementally reducing flyheight of the slider until contact is made between the slider and therecording medium. Once contact is made, an appropriate clearance is setsuch that slider is made to fly close to, but spaced apart from, thesurface of the medium during operation. It can be appreciated that forHAMR sliders, it is important to account for LIWP in order to avoiddetrimental contact between the slider and the medium.

The writing process implemented by a HAMR device generates hightemperatures at the ABS 114 proximate the NFT 112 and write pole 226, aswell as the hotspot 119 on the magnetic medium 118. The elevatedtemperatures associated with HAMR device operation results inthermochemical reactions between the recording head arrangement and themagnetic medium 118. For example, elevated temperatures at the head-diskinterface result in an increase of contaminants from a variety ofsources, including the lubrication that coats the magnetic medium 118.Globules of lubrication and other contaminants can form at the head-diskinterface, which tend to accumulate at or near locations of elevatedtemperature. Other contaminants that tend to accumulate at the head-diskinterface include silica, iron, iron-platinum, nickel, asperities, andother materials that are used to fabricate the magnetic medium. Dust andother ambient debris can also accumulate at the head-disk interface.

One problematic contaminant buildup region of the slider is located atand near the NFT 112 and the write pole 226 of the slider 100. As willbe further discussed below, this contaminant buildup region fans outfrom the NFT in a cross-track direction along the ABS 114, extendingfrom the NFT 112, past the write pole 226, and towards the trailing edgeof the slider. FIG. 5 is an AFM image of a HAMR slider 502 showing thisproblematic contaminant buildup region 506 of the slider 502. Thiscontaminant buildup region 506 is manifested as a contaminant plume 508originating at or near the NFT/write pole region 504 of the slider 502,and fanning out in a cross-track direction towards the trailing edge ofthe slider 502.

A writer contact sensor is typically situated at or near a writer closepoint of the ABS in the vicinity of the NFT/write pole region 504. Thewriter contact sensor is used for setting writer clearance, sensingchanges in slider fly height, and sensing contact between the slider andthe magnetic medium. In addition to sensing head-to-medium contactevents, the writer contact sensor can be configured to sense BLIWP andLLIWP. Because the writer contact sensor is typically situated withinthe contaminant buildup region 506 near the NFT/write pole region 504,contaminants can build up on the writer contact sensor. Contaminantbuildup on the writer contact sensor can cause an early contact detecttrigger, which leads to an incorrect zero reference being used as thewriter clearance setting. Contaminant buildup on the writer contactsensor can also render the writer contact sensor insensitive to BLIWPand LLIWP. Although various cleaning techniques have been developed inan attempt to remove contaminants from the ABS of a slider, contaminantbuildup on the ABS, including on the writer contact sensor, is areoccurring problem that resumes upon completion of a cleaningtechnique.

FIG. 6A is a schematic of various components of a HAMR slider, includinga split contact sensor, situated at or proximate an ABS of the slider inaccordance with various embodiments. The schematic shown in FIG. 6A is amedium-facing view of the ABS 602 of the slider 600. The portion of theslider 600 shown in FIG. 6A includes a write pole 610 situated proximatean NFT 612. A reader 618 is positioned up track of the NFT 612 in thedirection of a leading edge 604 of the slider 600. It is understood thatthe schematic view of the ABS portion shown in FIG. 6A is not to scale.

A split contact sensor 620 is situated between the write pole 610 and atrailing edge 606 of the slider 600. In broad terms, one or moreportions of the split contact sensor 620 is/are situated at or proximatethe ABS 602, while one or more portions of the split contact sensor 620is/are situated away from the ABS 602. The split contact sensor 620shown in FIG. 6A includes a first ABS section 622 and a second ABSsection 624, each of which is situated at or near (e.g., within about300 nm) the ABS 602. The first ABS section 622 is spaced apart from thesecond ABS section 624 in a cross-track direction by a gap, G. As can beseen in the cross-sectional view of FIG. 6B, the first ABS section 622is connected to the second ABS section 624 by a distal section 626. Thedistal section 626 of the split contact sensor 620 extends away from theABS 602 and into the body of the slider 600 (e.g., in a direction intothe page as is denoted by the solid circles on opposing ends of thefirst and second ABS sections 622, 624). More particularly, the firstand second ABS sections 622, 624 are oriented along a first plane thatis at or parallel with the ABS 602. One or both of the write pole 610and the NFT 612 can also be oriented along the first plane. The distalsection 626 of the split contact sensor 620 is oriented along a secondplane oblique to the first plane. In some configurations, the first andsecond planes can be orthogonal to one another.

The portion of the ABS 602 shown in FIG. 6A includes a contaminantbuildup region 640 that originates at or near an NFT/write pole region614 of the ABS 602 and extends in a direction towards the trailing edge606 of the slider 600. The contaminant buildup region 640 fans out in across-track direction as it extends from the NFT/write pole region 614towards the trailing edge 606 of the slider 600. The contaminant buildupregion 640 is a substantially V-shaped region defined by a vertex angle,β. A vertex of the V-shaped region 640 is situated at or proximate theNFT/write pole region 614, typically ahead of the NFT 612 (e.g., at ornear location A). The vertex angle, β, is defined between lines 642 and644 that originate at the vertex. Lines 642 and 644 define the peripheryof the contaminant buildup region 640. Although lines 642, 644 are shownas generally straight lines, it is understood that the periphery of thecontaminant buildup region 640 can be somewhat meandering. The magnitudeof the vertex angle, β, is related to the skew angle of the slider 600defined between extreme inner and outer diameter locations of themagnetic storage medium over which the slider 600 is positionable. Ingeneral, the vertex angle, β, can range between about +/−15° relative tolongitudinal axis 645. For example, the vertex angle, β, can range fromabout 15° to about 30°. In accordance with a different perspective, thevertex angle, β, can be defined as an angle between the NFT 612 andopposing ends (denoted by solid circles) of the first and second ABSsections 622, 624, such that the vertex angle, β, ranges between about+/−15° relative to longitudinal axis 645 (e.g., from about 15° to about30°).

As is shown in FIG. 6A, the split contact sensor 620 is positioned downtrack of the NFT/write pole region 614 between the write pole 610 andthe trailing edge 606 of the slider 600. It is desirable to position thesplit contact sensor 620 in close proximity to the NFT/write pole region614 in order to reliably detect contact between the slider 600 and amagnetic recording medium and, in some implementations, detectLaser-induced protrusion of the ABS 602. For example, in accordance withvarious embodiments, the split contact sensor 620 is positioned relativeto the NFT/write pole region 614 in order to sense (a) head-to-mediumcontact, (b) BLIWP, and (c) LLIWP. It has been determined by theinventors that positioning the split contact sensor 620 downtrack of theNFT 612 in a direction towards the trailing edge 606 with a spacing, S₁,of about 0.8 μm to 2 μm facilitates sensing of head-to-medium contact,BLIWP, and LLIWP by the split contact sensor 620. It is noted that asplit contact sensor 620 positioned ahead of the NFT 612, such as atlocation A shown in FIG. 6A, can provide sufficient detection ofhead-to-medium contact, but does not provide sufficient detection ofBLIWP and LLIWP.

It was found that a traditional contact sensor positioned between theNFT 612 and the trailing edge 606 with a spacing, S1, described aboveaccumulated contaminant buildup due to being positioned within thecontaminant buildup region 640. As was discussed previously, thecontaminant buildup on a traditional contact sensor degrades performanceof the contact sensor and leads to an early contact detect trigger. Thesplit contact sensor 620 is configured to provide sensing ofhead-to-medium contact, BLIWP, and LLIWP while avoiding thecontamination plume at the ABS 602 and concomitant contaminant buildup.As a result, the split contact sensor 620 produces a reliable contactdetection signal indicative of actual (rather than early) head-to-mediumcontact.

According to various embodiments, the first and second ABS sections 622,624 of the split contact sensor 620 are situated at or near a locationof the ABS 602 outside of the contaminant buildup region 640. Forexample, the first ABS section 622 extends along the ABS 602 in across-track direction to a location adjacent to peripheral line 642 ofthe contaminant buildup region 640. At this location, denoted by a solidcircle, the distal section 626 of the split contact sensor 620 extendsaway from the ABS 602 and into the body of the slider 600, therebyavoiding the contaminant buildup region 640 (see FIG. 6B). The distalsection 626 extends in a cross-track direction within the body of theslider 600 and connects with the second ABS section 624 at a locationadjacent the contaminant buildup region 640 (denoted by a solid circle).From this location adjacent the contaminant buildup region 640 denotedby a solid circle, the second ABS section 624 extends along the ABS 602in a cross-track direction.

As can be seen in FIGS. 6A and 6B, the points of connection (denoted assolid circles) between the distal section 626 and the first and secondABS section 622, 624 of the split contact sensor 600 define a gap, G, atthe ABS 602. The size, S₂, of the gap, G, is dependent on the width ofthe contaminant buildup region 640 at a location where the split contactsensor 600 is positioned at the ABS 602. Because the contaminant buildupregion 640 has a tapered shape, the size, S₂, of the gap, G, is relatedto the apex angle, β, and the spacing, S₁ between the NFT 612 and thesplit contact sensor 620. Generally, the size, S₂, of the gap, G, rangesfrom about 2 μm to about 8 μm. In general, the split contact sensor 620has an overall length, L, ranging from about 8 μm to about 20 μm.

In some embodiments, the slider 600 includes a structure 630 near theNFT/write pole region 614. For example, the writer of the slider 600 caninclude a yoke 630 which is in contact with, and magnetically coupledto, the write pole 610 (see, e.g., yoke 228 in FIG. 2). In some sliderimplementations, the yoke or other structure 630 can be in the sameplane (or close to the same plane) as the split contact sensor 620. Insuch embodiments, the distal section 626 of the split contact sensor 620can be positioned and shaped to extend around the periphery of at leasta portion of the yoke or structure 630. As such, the shape of the distalsection 626 of the split contact sensor 620 can conform to a shape ofthe periphery of the yoke or structure 630. The distal section 626 isspaced apart from the yoke or structure 630 to avoid shorting the splitcontact sensor 620. In some implementations, a dielectric material isdisposed between the distal section 626 and the yoke or structure 630 toprovide electrical isolation therebetween.

In some embodiments, the distal section 626 need not extend around andconform to the shape of the periphery of the yoke or structure 630. Asis shown in FIG. 6C, a dielectric material 632 can be disposed betweenthe distal section 626 and the yoke or structure 630 to provideelectrical isolation between the distal section 626 and the yoke orstructure 630. As such, the distal section 626 can traverse across theyoke or structure 630 rather than traversing around the periphery of theyoke or structure 630. In embodiments that include a yoke or otherstructure 630 that represents an obstruction to the distal section 626,the size, S₂, of the gap, G, of the split contact sensor 620 needs to beof sufficient size to accommodate the yoke or other structure 630. It isunderstood that the split contact sensor 620 can be implemented atlocations of the ABS 620 other than the NFT/write pole region 614. Forexample, the split contact sensor 620 can be positioned down track ofthe NFT/write pole region 614 in a region that includes a bottomcladding disk (BCD) situated proximate an optical waveguide of theslider 600. The distal section 626 of the split contact sensor 620 canextend into the body of the slider 600 and loop around the BCD volume,while the first and second ABS sections 620 and 624 are situated at ornear the ABS 602.

According to various embodiments, the split contact sensor 620 can be athermal sensor having a temperature coefficient of resistance (referredto herein as a TCR sensor). The split contact sensor 620 can be orcomprise, for example, a thin metallic element, such as a wire, having ahigh TCR. In some embodiments, the first and second ABS sections 620 and624 comprise a material having a high TCR, and the distal section 626comprises a material having a low TCR. The distal section 626 can beformed at the same time, and with the same low TCR material as, theleads that connect to the first and second ABS sections 620 and 624(see, e.g., leads 1110, 1112 in FIG. 11). In other embodiments, theentire split contact sensor 620 can comprise the same high TCR material.

In some configurations, the split contact sensor 620 is implemented as aDifferential-Ended Thermal Coefficient of Resistance (DETCR) sensor. ADETCR sensor is configured to operate with each of its two electricalcontacts (i.e., ends) connected to respective bias sources provided by apair of electrical bond pads of the slider 600. In other configurations,the split contact sensor 620 can be implemented as a ground-splittemperature coefficient of resistance (GSTCR) sensor, in which one endof the GSTCR is coupled to ground and the other is coupled to a biassource via an electrical bond pad of the slider 600. It is understoodthat other types of contact sensors are contemplated, including varioustypes of resistance thermal sensors, thermistors, and thermocouples, forexample.

FIG. 7 shows contact sensor signals generated by a conventional contactsensor with and without contaminant buildup. The contact sensor signalsare given in terms of dR/dP, where dR is a change in resistance of thecontact sensor and dP is a change in heater power. It is highlydesirable that a contact sensor signal have only a single, distinct lowpoint indicative of a head-to-medium contact event. Curve 700 representsthe contact sensor signal generated by the conventional contact sensorwithout contaminant buildup. As can be seen in FIG. 7, curve 700decreases generally linearly with decreasing head-to-medium clearance.Detecting a deviation from linearity in dR/dP and a minima (dR/dP_(MIN))702 indicates head-media contact and head-media caused cooling andfrictional heating. In practice, a detector of the HAMR device evaluatesthe dR/dP curve 700 to detect a minima of the curve 700, indicated by adR/dP_(MIN) 702 in FIG. 7. When the mimima 702 is detected, ahead-to-medium contact event can be declared. As can be seen in FIG. 7,curve 700 includes a single, distinct low point 702 indicative of ahead-to-medium contact event.

Curve 710 represents a contact sensor signal generated by theconventional contact sensor with contaminant buildup. As in the casewith curve 700, curve 710 decreases generally linearly with decreasinghead-to-medium clearance. Unlike curve 700, curve 710 includes more thanone, distinct low point indicative of a head-to-medium contact event.Rather, curve 710 includes a first low point 712 which, when detected,can cause an early contact detect trigger and premature declaration ofhead-to-medium contact. Depending on the sensitivity of the contactdetector, a second low point 714 of curve 710 may be detected as anearly (and false) indication of head-to-medium contact. Curve 710includes a third low point 716 which, when detected, is indicative of anactual head-to-medium contact event. Note the difference in dR/dP atpoint 716 of curve 710 relative to that at point 702 of curve 700. Thehigher value of dR/dP at point 716 of curve 710 it is due to thepresence of contaminant buildup between the contact sensor and themagnetic medium, which gives a false indication of the heater powerrequired to effect contact between the contact sensor (with no buildup)and the magnetic medium.

FIG. 8 shows contact sensor signals generated by a split contact sensoraccording to various embodiments with and without contaminant buildup.Curve 800 represents the contact sensor signal generated by the splitcontact sensor without contaminant buildup. Curve 810 represents thecontact sensor signal generated by the split contact sensor withcontaminant buildup. As can be seen in FIG. 8, curves 800 and 810 arenearly identical, with each curve 800, 810 having a single, distinct lowpoint 802/812. In fact, the location and magnitude of the low point 802of curve 800 is effectively the same as the location and magnitude ofthe low point 812 of curve 810. Curves 800, 810 of FIG. 8 demonstratethat the split contact sensor of the present disclosure provides areliable and consistent contact detect signal even with contaminantbuildup occurring within the contaminant buildup region of the ABS.

FIG. 9 is a perspective view of a split contact sensor in accordancewith various embodiments. The split contact sensor 900 is configured fordeployment at a location of the slider proximate the NFT/write poleregion of the ABS as previously described. The split contact sensor 900includes a first ABS section 902, which is situated at or near the ABSof the slider at a location previously described. The split contactsensor 900 includes a second ABS section 904, which is situated at ornear the ABS of a slider at a location previously described. A distalsection 906 of the split contact sensor 900 is connected at a first end903 of the first ABS section 902 and at a first end 907 of the secondABS section 904. The distal section 906 extends away from the ABS andinto the body of the slider so as to avoid the contaminant buildupregion of the ABS. The distal section 906 shown in FIG. 9 has thegeneral shape of the letter U, the Greek letter Omega, or an open loop.In some embodiments, the shape of the distal section 906 generallyconforms to a shape of a structure 914 of the slider (e.g., a yoke) thatis on the same plane as the split contact sensor 900. It is understoodthat the distal section can have any practical or useful shape. Adielectric material (e.g., 200 nm of Al₂O₃) can be disposed between thedistal section 906 and the structure 914 to provide electrical isolationbetween the distal section 906 and the structure 914.

The split contact sensor 900 includes a gap, G, defined along the ABSbetween respective first ends 903, 907 of the first and second ABSsections 902, 904. As was discussed previously, the gap, G, has aspacing sufficient to accommodate the width of the contamination plumedeveloped within the contaminant buildup region of the ABS. In theembodiment shown in FIG. 9, the gap, G, has a spacing of about 6 μm(e.g., 5.8 μm), and the split contact sensor 900 has a length, L, ofabout 20 μm.

As is further shown in FIG. 9, a second end 905 of the first ABS section902 is connected to a first electrical lead 910. A second end 909 of thesecond ABS section 904 is connected to a second electrical lead 912. Thefirst and second electrical leads 910, 912 are coupled to a pair ofelectrical bond pads of the slider. Also shown in FIG. 9 is readercontact sensor 920, which is positioned up track of the split contactsensor 900 in the direction of the leading edge of the slider. Thereader contact sensor 920 is connected to a pair of electrical leads922, 924. The electrical leads 922, 924 are coupled to a pair ofelectrical bond pads of the slider. In some embodiments, the readercontact sensor 920 and the split contact sensor 900 are coupled together(e.g., in series or parallel) and to the same pair of electrical bondpads of the slider.

In some embodiments, the first and second ABS sections 902 and 904comprise a material having a high TCR, and the distal section 906comprises a material having a low TCR. The distal section 906 can beformed at the same time, and with the same low TCR material as, theleads 910 and 912 that connect to the first and second ABS section ends905 and 909. In other embodiments, the distal section 906 is formed fromthe same material as that of the first and second ABS sections 902, 904.Materials having a relatively high TCR provide for enhanced temperatureand temperature change sensing by the split contact sensor 900. Suitablematerials include, but are not limited, metals such as Pt, Ru, Cu, Cr,Au, Al, W, Ni, NiFe, and Mo. Other non-metal materials may also be used,such as carbon nanotubes, indium tin oxide (ITO),Poly(3,4-ethylenedioxythiophene) (PEDOT), poly(styrene sulfonate) PSS,and graphene. Materials having a low TCR include Nichrome, constantan,manganin, and mercury.

In general, the TCR of the first and second ABS sections 902 and 904(e.g., the sensor portion of the split contact sensor 900) is higherthan the TCR of the leads 910 and 912. Preferably, the TCR of the firstand second ABS sections 902 and 904 is above about 0.3%/° C., and theTCR of the leads 910 and 912 is less than about 0.1%/° C. Acceptableperformance can be achieved when the TCR of the first and second ABSsections 902 and 904 is at least about 0.3%/° C., and the TCR of theleads 910 and 912 is about 0.2%/° C. or less.

FIG. 10 is a view of a split contact sensor in accordance with variousembodiments. The split contact sensor 1000, which was developed formodeling purposes, is configured for deployment at a location of theslider proximate the NFT/write pole region of the ABS as previouslydescribed. The split contact sensor 1000 includes a first ABS section1002, which is situated at or near the ABS of the slider at a locationpreviously described. The split contact sensor 1000 includes a secondABS section 1004, which is situated at or near the ABS of a slider at alocation previously described. A distal section 1006 of the splitcontact sensor 1000 is connected at a first end 1003 of the first ABSsection 1002 and at a first end 1007 of the second ABS section 1002. Thedistal section 1006 extends away from the ABS and into the body of theslider so as to avoid the contaminant buildup region of the ABS.

The distal section 1006 shown in FIG. 10 has the general shape of theletter U, the Greek letter Omega, or an open loop (in block form). Insome embodiments, the shape of the distal section 1006 generallyconforms to a shape of a structure 1014 of the slider (e.g., a yoke)which is on the same plane (or nearly the same plane) as the splitcontact sensor 1000. A dielectric material can be disposed in a gap(e.g., 0.5 μm in width) between the distal section 1006 and thestructure 1014 to provide electrical isolation therebetween. The splitcontact sensor 1000 can be formed of materials described hereinabove.

As is further shown in FIG. 10, a second end 1005 of the first ABSsection 1002 is connected to a first electrical lead 1010. A second end1009 of the second ABS section 1004 is connected to a second electricallead 1012. The first and second electrical leads 1010, 1012 are coupledto a pair of electrical bond pads of the slider. In some embodiments,the first and second ABS sections 1002 and 1004 comprise a materialhaving a high TCR, and the distal section 1006 comprises a materialhaving a low TCR. The distal section 1006 can be formed at the sametime, and with the same low TCR material as, the leads 1010 and 1012that connect to the first and second ABS section ends 1005 and 1009. Inother embodiments, the distal section 1006 is formed from the samematerial as that of the first and second ABS sections 1002, 1004.

The split contact sensor 1000 includes a gap, A, defined along the ABSbetween respective first ends 1003, 1007 of the first and second ABSsections 1002, 1004. The gap, A, has a spacing sufficient to accommodatethe width of the contamination plume developed within the contaminantbuildup region of the ABS. In the embodiment shown in FIG. 10, the gap,A, has a spacing of between about 2 μm and 4 μm (e.g., 3 μm), and thesplit contact sensor 1000 has a length, D, of about 12 μm. In the designof the split contact sensor 1000, the lengths B and C (e.g., both 0.375μm) at the respective first ends 1003, 1007 of the first and second ABSsections 1002, 1004 are matched to target a maximum active sensorresistance (e.g., ˜39Ω). It is noted that the diagonal cutouts at therespective first ends 1003, 1007 of the first and second ABS sections1002, 1004 have a width of 0.3 μm.

FIG. 11 is a perspective view of a split contact sensor in accordancewith various embodiments. Relative to the embodiments shown in FIGS. 9and 10, the split contact sensor 1100 provides for increased processmanufacturability and reduced cross-track separation between ABSsections of the split contact sensor 1100. The split contact sensor 1100is configured for deployment at a location of the slider proximate theNFT/write pole region of the ABS as previously described. The splitcontact sensor 1100 includes a first ABS section 1102 and a second ABSsection 1104, both of which are situated at or near the ABS of a sliderat a location previously described. A distal section 1106 of the splitcontact sensor 1100 is connected at a first end 1103 of the first ABSsection 1102 and at a first end 1107 of the second ABS section 1102. Thedistal section 1106 extends away from the ABS and into the body of theslider so as to avoid the contaminant buildup region of the ABS.

The distal section 1106 shown in FIG. 11 has the general shape of theletter U, the Greek letter Omega, or an open loop (in block form). Insome embodiments, the shape of the distal section 1106 generallyconforms to a shape of a structure 1114 of the slider (e.g., a yoke)which is on the same plane (or nearly the same plane) as the splitcontact sensor 1100. A dielectric material can be disposed in a gapbetween the distal section 1106 and the structure 1114 to provideelectrical isolation therebetween.

As is further shown in FIG. 11, a second end 1105 of the first ABSsection 1102 is connected to a first electrical lead 1110. A second end1109 of the second ABS section 1104 is connected to a second electricallead 1112. The first and second electrical leads 1110, 1112 are coupledto a pair of electrical bond pads of the slider. Also shown in FIG. 11is reader contact sensor 1120, which is positioned down track of thesplit contact sensor 1100 in the direction of the leading edge of theslider. The reader contact sensor 1120 is connected to a pair ofelectrical leads 1122, 1124. The electrical leads 1122, 1124 are coupledto a pair of electrical bond pads of the slider. In some embodiments,the reader contact sensor 1120 and the split contact sensor 1100 arecoupled together (e.g., in series or parallel) and to the same pair ofelectrical bond pads of the slider.

In some embodiments, the first and second ABS sections 1102 and 1104comprise a material having a high TCR, and the distal section 1106comprises a material having a low TCR. The distal section 1106 can beformed at the same time, and with the same low TCR material as, theleads 1110 and 1112 that connect to the first and second ABS sectionends 1105 and 1109. In other embodiments, the distal section 1106 isformed from the same material as that of the first and second ABSsections 1102, 1104.

The split contact sensor 1100 includes a gap, G, defined along the ABSbetween respective first ends 1103, 1107 of the first and second ABSsections 1102, 1104. The gap, G, has a spacing sufficient to accommodatethe width of the contamination plume developed within the contaminantbuildup region of the ABS. In the embodiment shown in FIG. 11, the gap,G, has a spacing of between about 2 μm and 4 μm (e.g., 3 μm), and thesplit contact sensor 1100 has a length, L, of about 9 μm (e.g., 8.8 μm).It is noted that the arcuate cutouts 1111 at the respective first ends1103, 1107 of the first and second ABS sections 1102, 1104 have adiameter of 1 μm.

Although reference is made herein to the accompanying set of drawingsthat form part of this disclosure, one of at least ordinary skill in theart will appreciate that various adaptations and modifications of theembodiments described herein are within, or do not depart from, thescope of this disclosure. For example, aspects of the embodimentsdescribed herein may be combined in a variety of ways with each other.Therefore, it is to be understood that, within the scope of the appendedclaims, the claimed invention may be practiced other than as explicitlydescribed herein.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsmay be understood as being modified either by the term “exactly” or“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein or, for example, within typical ranges ofexperimental error.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5) and any range within that range. Herein, the terms “upto” or “no greater than” a number (e.g., up to 50) includes the number(e.g., 50), and the term “no less than” a number (e.g., no less than 5)includes the number (e.g., 5).

The terms “coupled” or “connected” refer to elements being attached toeach other either directly (in direct contact with each other) orindirectly (having one or more elements between and attaching the twoelements). Either term may be modified by “operatively” and “operably,”which may be used interchangeably, to describe that the coupling orconnection is configured to allow the components to interact to carryout at least some functionality (for example, a radio chip may beoperably coupled to an antenna element to provide a radio frequencyelectric signal for wireless communication).

Terms related to orientation, such as “top,” “bottom,” “side,” and“end,” are used to describe relative positions of components and are notmeant to limit the orientation of the embodiments contemplated. Forexample, an embodiment described as having a “top” and “bottom” alsoencompasses embodiments thereof rotated in various directions unless thecontent clearly dictates otherwise.

Reference to “one embodiment,” “an embodiment,” “certain embodiments,”or “some embodiments,” etc., means that a particular feature,configuration, composition, or characteristic described in connectionwith the embodiment is included in at least one embodiment of thedisclosure. Thus, the appearances of such phrases in various placesthroughout are not necessarily referring to the same embodiment of thedisclosure. Furthermore, the particular features, configurations,compositions, or characteristics may be combined in any suitable mannerin one or more embodiments.

The words “preferred” and “preferably” refer to embodiments of thedisclosure that may afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful and is not intended to exclude other embodiments from the scopeof the disclosure.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

As used herein, “have,” “having,” “include,” “including,” “comprise,”“comprising” or the like are used in their open-ended sense, andgenerally mean “including, but not limited to.” It will be understoodthat “consisting essentially of” “consisting of,” and the like aresubsumed in “comprising,” and the like. The term “and/or” means one orall of the listed elements or a combination of at least two of thelisted elements.

The phrases “at least one of,” “comprises at least one of,” and “one ormore of” followed by a list refers to any one of the items in the listand any combination of two or more items in the list.

What is claimed is:
 1. An apparatus, comprising: a slider comprising anair bearing surface (ABS); a write pole situated at or near the ABS; anear-field transducer (NFT) situated at or near the ABS and proximatethe write pole; an optical waveguide configured to couple light from alight source to the NFT; and a contact sensor disposed on the ABSproximate the write pole and the NFT, the contact sensor comprising atleast one portion peripheral to a contaminant buildup region of the ABSand a section, connected to the at least one portion, that extends atleast partially in a cross-track direction while avoiding thecontaminant buildup region of the ABS.
 2. The apparatus of claim 1,wherein the contaminant buildup region defines a region of the ABS at ornear the NFT and the write pole.
 3. The apparatus of claim 1, wherein:the slider comprises a leading edge and a trailing edge opposing theleading edge; and the contaminant buildup region defines a region of theABS fanning out in a cross-track direction from a contaminant sourcelocation of the ABS towards the trailing edge of the slider.
 4. Theapparatus of claim 1, wherein the section of the contact sensor extendsaway from the ABS and into a body of the slider.
 5. The apparatus ofclaim 1, wherein the section of the contact sensor extends at leastpartially around a structural element disposed on the ABS.
 6. Theapparatus of claim 1, wherein: the write pole has a cross-track width;and the section of the contact sensor has a cross-track width greaterthan the cross-track width of the write pole.
 7. The apparatus of claim1, wherein: the section of the contact sensor is coupled to, andpositioned between, first and second portions of the contact sensor; agap is defined between the first and second portions; and a structuralelement of the slider is disposed in the gap.
 8. The apparatus of claim1, wherein: the slider comprises a leading edge and a trailing edgeopposing the leading edge; and the contact sensor is situated betweenthe write pole and the trailing edge.
 9. The apparatus of claim 1,wherein: the section of the contact sensor is coupled to, and positionedbetween, first and second portions of the contact sensor; an angle isdefined between the NFT and opposing ends of the first and secondportions; and the angle ranges from about 15 degrees to about 30degrees.
 10. An apparatus, comprising: a slider comprising an airbearing surface (ABS); a write pole situated at or near the ABS; anear-field transducer (NFT) situated at or near the ABS and proximatethe write pole; an optical waveguide configured to couple light from alight source to the NFT; and a contact sensor disposed at a region ofthe ABS that includes a metallic optical structure situated proximatethe optical waveguide and spaced away from a region of the ABS thatincludes the write pole and the NFT, the contact sensor comprising atleast one portion peripheral to a contaminant buildup region of the ABSand a section, connected to the at least one portion, that extends atleast partially in a cross-track direction while avoiding contaminantbuildup region of the ABS.
 11. The apparatus of claim 10, wherein themetallic optical structure comprises a bottom cladding disk (BCD)situated proximate the optical waveguide.
 12. The apparatus of claim 10,wherein: the slider comprises a leading edge and a trailing edgeopposing the leading edge; and the contaminant buildup region defines aregion of the ABS fanning out in a cross-track direction from acontaminant source location of the ABS towards the trailing edge of theslider.
 13. The apparatus of claim 10, wherein the section of thecontact sensor extends into a body of the slider and extends at leastpartially around the metallic optical structure.
 14. The apparatus ofclaim 10, wherein: the contact sensor comprises a first portion, asecond portion, and the section coupled to, and positioned between, thefirst and second portions; the first and second portions are situated ator near the ABS; and the section of the contact sensor extends into abody of the slider and extends at least partially around the metallicoptical structure.
 15. An apparatus, comprising: a slider comprising anair bearing surface (ABS); a write pole situated at or near the ABS; anear-field transducer (NFT) situated at or near the ABS and proximatethe write pole; an optical waveguide configured to couple light from alight source to the NFT; and a contact sensor disposed on the ABS, thecontact sensor comprising a first portion, a second portion, and asection coupled to, and positioned between, the first and secondportions, the first portion situated peripheral to a first side of acontaminant buildup region of the ABS, the second portion situatedperipheral to a second side of the contaminant buildup region opposingthe first side, and the section of the contact sensor arranged to avoidthe contaminant buildup region of the ABS.
 16. The apparatus of claim15, wherein: the slider comprises a leading edge and a trailing edgeopposing the leading edge; and the contaminant buildup region defines aregion of the ABS fanning out in a cross-track direction from acontaminant source location of the ABS towards the trailing edge of theslider.
 17. The apparatus of claim 15, wherein: the first and secondportions of the contact sensor are situated on a first plane of the ABS;and the section of the contact sensor is situated on a second plane ofthe ABS different from the first plane.
 18. The apparatus of claim 17,wherein the second plane is oblique or orthogonal to the first plane.19. The apparatus of claim 15, wherein the section of the contact sensorextends at least partially around a metallic structure of the slider.20. The apparatus of claim 15, wherein the section of the contact sensorextends into a body of the slider and extends at least partially arounda metallic structure of the slider.